Spray booth



March 3, 1964 J. A. PAASCHE SPRAY BOOTH (SELF CLEANING) 4 Sheets-Sheet lINVENTOR Qflaa'ce Jim; v

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Filed Aug. 5, 1960 March 3, 1964 J. A. PAASCHE SPRAY BOOTH (SELFCLEANING) 4 Sheets-Sheet 2 Filed Aug. 5. 1960 INVENTOR 5726 dj aa5ckevfiw/w MW ww HHMWHHWWWHHI WHUWWHWH Hwnwnnmnmwmwnw 5 5 i Mardl 1964 J. A.PAASCHE SPRAY BOOTH (SELF CLEANING) 4 Sheets-Sheet 3 Filed Aug. 5, 1960II/IIIII'IIIIII'I INVENTOR- fiaace March 1964 J. A. PAASCHE SPRAY BOOTH(SELF CLEANING) t N NW m N% 11 I ll H w & {H1111 M I I i I I i \n p Q.mm u w v a 7 Filed Aug. 5, 1960 United States Patent 3,123,455 SPRAYBOOTH (SELF CLEANENG) liens A. Paasche, 310 Greenleaf, Wilmette, Ill.Filed Aug. 5, 1960, Ser. No. 47,849 Claims. ((Il. 55-228} The presentinvention relates to spray coating booths which define working spacewithin which objects are positioned and coated with atomized droplets ofa coating liquid directed onto the objects from spray guns or the like.In such spray coating operations, there is almost invariably anoverspray of atomized droplets of coating material which do not impingeupon the object or objects being coated. This overspray tends to collecton the structure defining the working space in which the coating isperformed and contaminates the atmosphere surrounding the sprayingoperation. This contamination of the environment can create manyproblems and undesirable conditions, some of which are hazardous.

To minimize contamination of the environment by the overspray from suchspray coating operations, spray booths have been developed which makeuse of water curtains to shield the working space defining structurefrom the overspray and which continuously scavenge the working spacewith air that is subsequently washed to remove the entrained particlesof coating material. The maintenance of the protective curtains or"water in such booths and the washing of the scavenging air has requiredthe circulation of wash water or scavenging liquid through the booths ata high volumetric rate. To prevent the water used as a scavenging liquidfrom becoming overcontaminated with entrained coating material it hasbeen necessary to provide some means for removing the coating materialfrom the water circulated through a spray booth of this character.

One object of the invention is to provide a spray coating boothincorporating an improved construction and utilizing novel features ofoperation to provide worthwhile advantages in the construction and useof the booth.

Another object is to provide an improved spray coating booth of thecharacter recited in which an improved construction provides for a moreeificient and highly advantageous removal of coating material from thescavenging liquid, which is circulated through the booth to preventcontamination of the environment by the overspray from sprayingoperations in the booth.

A further object of the invention is to provide a spray coating booth ofthe character recited in which a more efficient cleaning of coatingmaterial from the scavenging liquid is achieved in an improved manner,which simplifies the construction and minimizes the size of the liquidcleaning structure while at the same time greatly increasing thevolumetric rate at which liquid can be cleaned and circulated throughthe booth.

A more specific object is to provide an improved spray coating booth asrecited in the preceding objects in which a fully effective filtering ofthe entire flow of scavenging liquid through the booth is provided in amanner which necessitates actual filtering of only a fraction of theliquid flow through the booth.-

Other objects and advantages will become apparent from the followingdescription of the exemplary embodiment of the invention illustrated inthe drawings, in which:

FEGURE l is a perspective view of the spray coating booth forming theillustrated embodiment of the invention, certain portions of the boothstructure being broken away for clearness in illustration;

FIG. 2 is a front elevational view of the booth shown in FIG. 1;

FIG. 3 is a transverse sectional view taken along the line 33 of FIG. 2;

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FIG. 4 is a perspective view of a typical panel flushing nozzle used inthe booth;

FIG. 5 is a fragmentary sectional view taken along the line 5-5 of FIG.1;

FIG. 6 is a fragmentary sectional view taken along the line 66 of FIG.5;

FIG. 7 is a fragmentary sectional view taken along the line 7-7 of FIG.1; and

FIG. 8 is a fragmentary perspective view taken along the line 88 of FIG.1.

eferring to the drawings in greater detail, the spray booth 10 formingthe exemplary embodiment of the invention illustrated defines aninternal working space 12, FIGS. 1-3, within which a typical article 14to be coated is positioned by any suitable means (not shown) and coatedwith a coating liquid atomized and directed toward the object by a spraygun to. As shown, the working space 12' has a rectilinear form and isopen only along the front side of the booth. This space is defined bybooth structure including a ceiling 18, a floor panel 29, a rear side orback panel 22, and two side panels or end walls 24, 26.

Low velocity coating particles which do not impinge on the article beingcoated are swept from the working space 12 by a current of scavengingair which is sucked through the working space into an air Washer 28 atthe rear side of the booth ill.

The air washer 28 extends horizontally along the full length of thebooth ill and is separated from the working space M; within the boothonly by the rear panel 22: which extends downwardly and rearwardly, FIG.3, to the lower edge of the rear panel, which terminates a substantialdistance above the level of the floor panel 20. This provides alongitudinal opening 3% between the rear lower portion of the workingspace 12 and the bottom of the air washer 28.

Air is drawn up through the washer 28 by an exhaust fan 32 which causesthe air to flow through a transverse diffuser 34 formed by fenestratedbaflling extending the full length of the washer just above the loweredge of the table 22. A finely divided spray of water is playeddownwardly onto the diffuser 34 by means of a series of nozzles 36depending from a longitudinal manifold 38 extending through the washerabove the diffuser. Droplets of water entrained in the air stream areremoved from the air by a horizontal series of air drying bafiles 46which overlie the manifold 38.

Irnpingement of particles of coating material onto the floor panel 20and onto the upright panels Z2, Z4 and 26 bounding the working space '12is prevented by a continuous flushing of these panels with moving sheetsor curtains of water.

Thus, the floor panel 29' is continuously flushed with water directedonto the panel from a series of nozzles 42. projecting rearwardly from ahorizontal manifold 44 extending along the front edge of the bottompanel. The upright panel 22, 24, and 26 are flushed with Water directeddownwardly onto these panels by nozzles 46 depending from horizontalmanifolds 48, 50, 52 for the respective upright panels.

Each of the nozzles 42, 4-6 is designed to direct a flat divergingstream of water onto an adjacent portion of the coacting panel. Atypical nozzle 46 is illustrated in FIG. 4. As shown it is flattened atits projecting end and shaped to define a generally flat outlet 54 forprojecting a flat stream of water. The streams of water from adjacentnozzles merge together to form continuous curtains of water flowing overthe panels.

The bottom panel 2-6 is inclined rearwardly to discharge flushing waterfrom the working space 12 into a longitudinal runway 56 formed by alongitudinally inclined bottom 58 in the washer 29, which is locatedbelow the rear edge of the bottom panel 2% as shown in FIG. 3 andinclined longitudinally toward one end of the booth. The water which iscollected into the channel 56 from the Washer 28 and from the workingspace defining panels is directed into a fiow channel 60, FIGS. 1 and5-7, designed to produce a generally nonturbulent, laminar flow patternin the stream of liquid passing through the channel.

Preferably, the channel 60 is disposed in overlying relation to anelongated reservoir 62 and comprises two vertical side walls 64, 66which extend upwardly from a fiat plate 68 defining the bottom of thechannel.

The channel 6t} is turned at a right angle to the runway 56 and extendsforwardly from one end of the runway along one end of the booth as shownin FIG. 1. The rear portion of the channel wall 66 is curvedprogressively toward the washer 28 to connect with the rear side edge ofthe washer at the outlet of the runway 56.

scavenging water is discharged from the runway 56 into the channel 66'where it is turned by the wall 6t) to flow along the length of thechannel. The bottom 68 of the channel is inclined downwardly at a smallangle in the forward direction to provide a controlled velocity of flowof liquid in the channel.

As the liquid flows forwardly in the channel 60 in a generallynonturbulent manner, the coating material entrained in the scavengingliquid tends to concentrate in the upper portion of the flow stream.

The upper portion of the liquid stream in the channel 60, in which theentrained coating material is concentrated, is segregated from theunderlying portion of the stream, which is relatively clean anduncontaminated with entrained coating material. This is accomplished bymeans of a skimmer or a separator 70 which defines a horizontal flowdividing or separating edge '72, FIGS. 5 and 7, that is supported intransverse vertically spaced relation to the channel bottom 68 a shortdistance ahead of the outlet end of the channel. The separator edge 72extends substantially across the entire width of the channel 60 and issomewhat inclined upwardly and rearwardly at its leading edge to effectan upward displacement of an upper stratum 74 of the liquid flow streamin the channel 60. The portion of the channel fiow stream which passesunder the separator edge *72 is discharged from the outlet end of thechannel directly into the underlying reservoir 62 as illustrated inFIGS. 5 and 7.

The ratio of the volume of liquid flowing across the separator edge 72relative to the volume of liquid flowing under this edge can be adjustedby adjusting the vertical spacing of the edge 72 from the channel bottom63. This is accomplished by means of vertically adjustable supports 76,78 for the forward end of the separator 70, which supports the leadingseparator edge 72.

Rearwardly of the edge 72, the separator '70 defines a liquid collectingand cleaning basin 80 which receives the liquid flowing into theseparator across the separator edge 72. The bottom of the liquidcollector or cleaning portion 80 of the separator 70 is formed by agenerally flat metallic filter 82. The filter 82 extends beyond therunway 60 in overlying relation to the reservoir 62 and is supportedalong its respective edges by three side walls 84 of the separator 7t?and by a transverse support bar 86 extending across the forward end ofthe separator at the rear of the separator edge 72 as shown in FIG. 7.The water in the liquid flowing across the edge 72 into the collectingbasin 8% immediately flows down through the filter 82 into the reservoir62. The coating material entrained in the liquid is retained by thefilter 82 and collects to form a sludge which is supported and preventedby the filter from dropping into the reservoir.

The separator 7-0 is designed to be lifted from its support on the upperedge of the reservoir 62 and dumped to remove the sludge collected onthe filter screen 82.

A pump 90 driven by an electric motor 92 pumps scavenging water from anintake 96 in the reservoir 62 into the previously described manifoldsleading to the nozzles 36 in the air washer and the flushing nozzles 46for the working space defining panels.

Even though only a fraction of the liquid circulated through the boothis filtered, the concentration of the entrained coating material in thatportion of the liquid which is filtered provides an efiective and highlysatisfactory removal of coating material from the circulating scavengingfluid. This makes for greater efficiency in operation and provides forcirculation of liquid at a high volumetric rate while at the same timeminimizing the size and simplifying the construction of the entireinstallation, including the means used to clean the scavening liquid.

It will be appreciated that the invention is not necessarily limited touse of the particular construction illustrated but includes the use ofvariants and equivalents within the scope of the invention as defined inthe claims.

The invention is claimed as follows:

1. Apparatus for use in the spray coating of objects, comprising, incombination; means defining an at least partially enclosed spray coatingspace and including a rearwardly inclined lioor panel, a rear panel, andtwo end panels; means defining an air washer separated from said sprayspace by said rear panel, said rear panel being inclined downwardly andrearwardly and terminating above the level of said floor panel toprovide communication between the lower rear portion of said space andsaid air washer, means for moving air from said space through saidwasher to exhaust, said washer including washing liquid spray means, adiffuser located upstream of said spray means with respect to the flowof air through said washer and air drying means located downstream ofsaid spray means with respect to the air flow through the Washer,flushing nozzle means arranged to direct curtains of washing liquidacross said space defining panels, a runway in the bottom of said washerarranged to collect liquid discharged from said air washer spray meansand from said flushing nozzle means, means defining a flow channelarranged to receive a continuous stream of washing liquid from saidrunway, said channel being designed to provide a generally laminar flowof liquid therethrough, means forming a generally horizontal separatoredge extending transversely across said channel in spaced relation tothe bottom thereof to effect a division of the liquid stream flowingthrough said channel, means for adjusting said separator edge verticallyto adjust tie vertical position at which the channel flow stream isdivided, reservoir means arranged to collect liquid flowing from saidchannel from below said separator edge, filtering means arranged toreceive liquid flowing across said separator edge and filter entrainedcoating material therefrom and return the filter liquid to saidreservoir, and pumping means for supplying liquid from said reservoir tosaid spray means and said flushing nozzle means.

2. Apparatus for use in the spray coating of objects, comprising, incombination; means defining an at least partially enclosed spray coatingspace and including a floor panel, a rear panel, and two end panels;means defining an air washer situated alongside said space andcommunicating with said space, means for effecting movement of airthrough said space and through said washer, said washer including meansfor spraying washing liquid into the air flowing through the washer,flushing nozzle means arranged to direct curtains of washing liquidacross said space defining panels, a runway in the bottom of said washerarranged to collect liquid discharged from said spraying means and fromsaid flushing nozzle means, means defining a flow channel arranged toreceive a continuous stream of washing liquid from said runway, saidchannel defining means having a smooth construction designed to providea substantially laminar flow of liquid therethrough, means forming agenerally horizontal separator edge extending transversely across saidchannel in spaced relation to the bottom thereof to efifect a divisionof the liquid stream flowing through said channel, means for effecting avertical adjustment of said separator edge with respect to the bottom ofsaid channel to vary the ratio of the liquid flowing over and under saidseparator edge, filtering means arranged to receive liquid flowingacross said separator edge and filter entrained coating materialtherefrom, and means for returning to said spraying means and to saidflushing nozzle means liquid filtered by said filtering means and liquidflowing from said channel from below said separator edge.

3. Apparatus as set forth in claim 2 and further including meanssupporting said filtering means for quick removal thereof.

4. Apparatus as set forth in claim 3 wherein the means for supportingthe filtering means comprises a plurality of outwardly disposed meansadjacent the upper portion of said filtering means and having downwardlydisposed abutment surfaces engageable with fixed abutment sur- 6 facesadjacent said filtering means for supporting said filtering means insuspended position.

5. Apparatus as set forth in claim 4 wherein the downwardly disposedabutment surfaces comprise the lower ends of screw threaded members foradjusting the height at which said filtering means is suspended, andalso comprising in part the means for effecting vertical adjustment ofthe separator edge.

References Cited in the file of this patent UNITED STATES PATENTS1,709,291 Vidler Apr. 16, 1929 2,086,514 Saunders et al. July 6, 19372,557,064 Alexander June 19, 1951 2,660,317 Mork et al. Nov. 24, 19532,788,954 Paasche Apr. 16, 1957

1. APPARATUS FOR USE IN THE SPRAY COATING OF OBJECTS, COMPRISING, INCOMBINATION; MEANS DEFINING AN AT LEAST PARTIALLY ENCLOSED SPRAY COATINGSPACE AND INCLUDING A REARWARDLY INCLINED FLOOR PANEL, A REAR PANEL, ANDTWO END PANELS; MEANS DEFINING AN AIR WASHER SEPARATED FROM SAID SPRAYSPACE BY SAID REAR PANEL, SAID REAR PANEL BEING INCLINED DOWNWARDLY ANDREARWARDLY AND TERMINATING ABOVE THE LEVEL OF SAID FLOOR PANEL TOPROVIDE COMMUNICATION BETWEEN THE LOWER REAR PORTION OF SAID SPACE ANDSAID AIR WASHER, MEANS FOR MOVING AIR FROM SAID SPACE THROUGH SAIDWASHER TO EXHAUST, SAID WASHER INCLUDING WASHING LIQUID SPRAY MEANS, ADIFFUSER LOCATED UPSTREAM OF SAID SPRAY MEANS WITH RESPECT TO THE FLOWOF AIR THROUGH SAID WASHER AND AIR DRYING MEANS LOCATED DOWNSTREAM OFSAID SPRAY MEANS WITH RESPECT TO THE AIR FLOW THROUGH THE WASHERFLUSHING NOZZLE MEANS ARRANGED TO DIRECT CURTAINS OF WASHING LIQUIDACROSS SAID SPACE DEFINING PANELS, A RUNWAY IN THE BOTTOM OF SAID WASHERARRANGED TO COLLECT LIQUID DISCHARGED FROM SAID AIR WASHER SPRAY MEANSAND FROM SAID FLUSHING NOZZLED MEANS, MEANS DEFINING A FLOW CHANNELARRANGED TO RECEIVE A CONTINUOUS STREAM OF WASHING LIQUID FROM SAIDRUNWAY, SAID CHANNEL BEING DESIGNED TO PROVIDE A GENERALLY LAMINAR FLOWOF LIQUID THERETHROUGH, MEANS FORMING A GENERALLY HORIZONTAL SEPARATOREDGE EXTENDING TRANSVERSELY ACROSS SAID CHANNEL IN SPACED RELATION TOTHE BOTTOM THEREOF TO EFFECT A DIVISION OF THE LIQUID STREAM FLOWINGTHROUGH SAID CHANNEL, MEANS FOR ADJUSTING SAID SEPARATOR EDGE VERTICALLYTO ADJUST THE VERTICAL POSITION AT WHICH THE CHANNEL FLOW STREAM ISDIVIDED, RESERVOIR MEANS ARRANGED TO COLLECT LIQUID FLOWING FROM SAIDCHANNEL FROM BELOW SAID SEPARATOR EDGE FILTERING MEANS ARRANGED TORECEIVE LIQUID FLOWING ACROSS SAID SEPARATOR EDGE AND FILTER ENTRAINEDCOATING MATERIAL THEREFROM AND RETURN THE FILTER LIQUID TO SAIDRESERVOIR, AND PUMPING MEANS FOR SUPPLYING LIQUID FROM SAID RESERVOIR TOSAID SPRAY MEANS AND SAID FLUSHING NOZZLE MEANS.